Evaluating the performance of a deterministic daily rainfall–runoff model in a low-flow context
✍ Scribed by V. Y. Smakhtin; K. Sami; D. A. Hughes
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 281 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0885-6087
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✦ Synopsis
The characterization of a stream's low-¯ow regime is required for ecological purposes, water quality studies and various other water projects. If observed stream ¯ow records are insucient, low-¯ow characteristics may need to be estimated from simulated daily stream ¯ow time-series. The model employed should conceptualize low-¯ow generation mechanisms and surface±subsurface interactions adequately. The ability of the model to simulate low-¯ow regimes may be assessed by means of various low-¯ow analysis techniques. This paper illustrates the approach using the example of the physically based, semi-distributed VTI daily rainfall±runo model. The model has been applied to ®ve perennial headwater catchments in South Africa, which are located in dierent parts of the country, represent dierent physiographical environments and are characterized by dierent base¯ow responses. The model simulations are evaluated in terms of both conventional goodness-of-®t criteria and several low-¯ow measures such as recession characteristics, base¯ow volumes, ¯ow duration curves and continuous low-¯ow events below speci®ed threshold discharges. For all the catchments considered the model has been found to perform successfully in terms of conventional ®t statistics and ¯ow duration curves. However, its ability to reproduce recession characteristics and continuous low-¯ow spells appears to be less satisfactory. This suggests that daily model simulations should be evaluated by low-¯ow criteria, which are frequently ignored in water resource assessment practices.